Is this your sister 答语为什么要用it is.

Is this your sister 答语为什么要用it is. Is this/that your sister 的答语是Yes,it is./ No,it isn’t 为什么要用it Is this your sister?的答语是? is this your sister的答语是 is this your sister?的答语为什么是Yes,it/she is.,两种人称,it,she都可以呢? 请问Is this your sister?的答语是 Yes,it is还是Yes,she is. Is this your sister?的答语是Yes,it/she is. 当问句为"Is that your sister?"时,答语为什么? Is this your sister 1人同问 Is this/that your sister 的答语是Yes,it is./ No,it isn’t 为什 is this your pencil-box?的答语 Is this your father?的答语